The LZB failure changed operating conditions on the Madrid-Seville high-speed line, where at least 69 people died and more than 100 were injured in Wednesday’s crash at Urda, Toledo. The collision occurred at about 08:53 on 28 October, near kilometre point 118+800 on line 010. Initial inquiries have examined the system failure, which began at about 08:31, though its precise role in the collision remains under investigation. AITAT’s preliminary estimate puts the Renfe AVE’s impact speed between 160 and 200 kilometres per hour.
Semaf has asked the Agencia Estatal de Seguridad Ferroviaria (AESF) to urgently revise the rules for LZB and related aspects of ERTMS. The union wants normal running barred when a system failure could leave two trains in the same railway section, known as a cantón.
According to initial information from the Autoridad Independiente para la Investigación Técnica de Accidentes e Incidentes Ferroviarios, Marítimos y de Aviación Civil (AITAT), LZB stopped working at 8.31 on Wednesday. The outage affected six trains across roughly 63 kilometres of line. Traffic then switched from LZB’s continuous cab signalling to Bloqueo de Señalización Lateral (BSL), which relies on signals beside the track. The line’s LZB equipment dates to the Madrid-Seville route’s opening in 1992. Transport Minister Óscar Puente said the outage brought trains in the surrounding section to a standstill because the automatic train-protection equipment is designed to operate on fail-safe principles. ASFA also supervises certain signals and can intervene in train braking.
During the changeover, the Centro de Regulación y Control (CRC) of ADIF exchanged information with the drivers. Reports say the Renfe AVE and the Iryo train were inside the same cantón. Trackside signals govern entry to each section. They may not prevent a collision if two trains are already inside it. Investigators are examining how the control centre and drivers interacted with BSL signals, while also assessing ASFA’s role. That includes reports that the AVE encountered a green signal without automatic braking being triggered.
One issue for investigators is the control centre’s reported authorisation for the AVE to resume normal running after the LZB failure. Published accounts say it could travel at up to 200 kilometres per hour under that instruction, rather than proceeding at a speed that required the driver to be able to stop for any obstacle or vehicle in view. Investigators are also examining whether the AVE’s movement authority was withdrawn after the Iryo remained stopped. AITAT has opened case 146/2026, classifying the event as a serious train collision. Its inquiry covers the technical failure, the switch to BSL, traffic-management decisions and organisational factors. A separate report covered the judge’s black-box seizure order.
The Iryo train was also reportedly authorised to resume circulation but did not move before the collision. Investigators still have to establish why it could not start, what the control centre knew about the trains’ positions and whether the instructions followed the procedures for this type of failure. AITAT’s inquiry is expected to take up to a year before publication of a final report. The technical investigation is separate from the judicial proceedings, which include preserving and examining the trains’ black boxes and other evidence.
